The p21/CDKN1/WAF1/CIP1 protein (El-Deiry, W. S.; et al. Cell 75: 817-825, 1993; Harper, J. W.; et al. Cell 75: 805-816, 1993; Huppi, Ket al. Oncogene 9: 3017-3020, 1994) is a cell cycle control protein that inhibits cyclin-kinase activity, is tightly regulated at the transcriptional level by p53, and mediates p53 suppression of tumor cell growth. Along with p53, p21 appears to be essential for maintaining the G2 checkpoint in human cells (Bunz, F.; Dutriaux, A.; et al. Science 282:1497-1501, 1998). Sequences of p21 are well-conserved throughout evolution, and have been identified in species as diverse as human (Genbank Identifier 13643057), Drosophila melanogaster (GI# 1684911), Caenorhabditis elegans (GI#4966283), and yeast (GI#2656016).
The hydrolytic dehalogenases catalyse a nucleophilic displacement reaction, with water as the sole co-substrate. They are divided into haloalkane dehalogenases and haloacid dehalogenases (HAD). HADs belong to a large superfamily of hydrolases with diverse substrate specificity, which also includes epoxide hydrolases, phosphoglycolate phosphatases, histidinol phosphate phosphatases, nitrophenyl phosphatases and numerous putative proteins. The epoxide hydrolases (EH) add water to epoxides, forming the corresponding diol. HADH (C20orf147) is a member of the haloacid dehalogenase or epoxide hydrolase family
The ability to manipulate the genomes of model organisms such as Drosophila provides a powerful means to analyze biochemical processes that, due to significant evolutionary conservation, have direct relevance to more complex vertebrate organisms. Due to a high level of gene and pathway conservation, the strong similarity of cellular processes, and the functional conservation of genes between these model organisms and mammals, identification of the involvement of novel genes in particular pathways and their functions in such model organisms can directly contribute to the understanding of the correlative pathways and methods of modulating them in mammals (see, for example, Mechler B M et al., 1985 EMBO J 4:1551-1557; Gateff E. 1982 Adv. Cancer Res. 37: 33-74; Watson K L., et al., 1994 J Cell Sci. 18: 19-33; Miklos G L, and Rubin G M. 1996 Cell 86:521-529; Wassarman D A, et al., 1995 Curr Opin Gen Dev 5: 44-50; and Booth D R. 1999 Cancer Metastasis Rev. 18: 261-284). For example, a genetic screen can be carried out in an invertebrate model organism having underexpression (e.g. knockout) or overexpression of a gene (referred to as a “genetic entry point”) that yields a visible phenotype. Additional genes are mutated in a random or targeted manner. When a gene mutation changes the original phenotype caused by the mutation in the genetic entry point, the gene is identified as a “modifier” involved in the same or overlapping pathway as the genetic entry point. When the genetic entry point is an ortholog of a human gene implicated in a disease pathway, such as p21, modifier genes can be identified that may be attractive candidate targets for novel therapeutics.
All references cited herein, including sequence information in referenced Genbank identifier numbers and website references, are incorporated herein in their entireties.